In the past, a number of mistakes have been commonly made in the design of slabs on a grade. These mistakes have resulted in extensive concrete cracking within a few days or months after installation. These design mistakes typically occur at contraction, isolation, or construction joints.
A discussion of these problems is set forth further presented in a detailed article entitled: "Avoiding Common Mistakes in Concrete Joint Design" appearing in Plant Engineering on Jan. 11, 1990 and attention is directed to this writing for further background concerning the state-of-the-art. My invention concerns certain improvements for solving at least some of the problems there discussed.
It will be appreciated that there is a substantial cost for repairing these types of failures in a busy facility, and for this reason it has been necessary to give considerable attention to attempt to avoid these problems.
My new and improved slab joint system structure herein disclosed relates to an integrated use of specially designed slab edge forms, a slab joint shear bar and, alternatively, an accessory lumber bracket to provide in combination a unique delivery apparatus to apply continuous vertical shear resistance yet allow lateral mobility between two poured in place concrete slabs.
My slab joint apparatus is comprised of: Two (2) channel-shaped slab edge forms which are used to hold the slab joint shear bar during curing of the slab. These have been referred to as slab joint edge forms in this writing.
An expendable continuous joint shear bar which is left in the slab and is encased in the concrete of the subsequent slab is provided. This bar is secured and held in proper position by my new slab joint form structure in the several embodiments herein disclosed.
According to certain features of my invention, accessory brackets can be used in place of the channel-shaped edge forms for filler areas or as an alternate to the channel-shaped edge forms. These components can be referred to as slab joint lumber brackets.